Micro-filters are used, particularly in medicine and biotechnology, to separate and collect very small particles, such as cells, suspended or dissolved in a fluid. For such purposes, micro-filters are often needed with passageways of specific shapes and with an internal diameter on the order of 1 micron and larger.
A variety of methods are presently known for making micro-filters. One such method is to make a mold using integrated circuits (IC) processing and lithographic processes. This mold can be formed by using well known "mask and etch technology" to build up a plurality of layers which are subsequently separated from the base substrate. The resultant mold may then be filled with plastic to form a precision micro-filter. The resultant micro-filter, however, tends to have high internal strain. Furthermore, this manufacturing technique for making a micro-filter tends to be expensive and thus non-economical.